Hyperpolarized 129Xe MRI: Introduction, History and New Directions

Hyperpolarized gas MRI is now emerging as a powerful clinical research tool at several medical centers around the world. By enhancing the magnetic resonance signal of inert gases, 3D breath-hold imaging of pulmonary function becomes possible. The technology has largely been driven by 3He MRI, which has shown exquisite abilities to evaluate pulmonary function regionally and non-invasively. It is intrinsically sensitive to the functioning of the smallest airways where early disease originates. By exploiting simple inhalation of inert gases, it can be used to conduct longitudinal studies of disease progression and therapy response that were previously not possible. However, recent crises in 3He supply have forced an abrupt transition to using hyperpolarized 129Xe, which is present in our atmosphere in unlimited quantities. But beyond serving as a mere replacement for 3He, 129Xe has fascinating properties, which we are now positioned to exploit. Namely, its solubility in biological tissues and accompanying range of chemical shifts open up a far richer range of function that can be addressed, and provide a new window on pulmonary gas exchange. Hyperpolarized gas MRI has had a long and rich development history, as well as its share of challenges. Thus, in this talk I will endeavor not only to introduce the technology and its current state-of-the-art and direction, but also revisit the history of its development.